Peracetic Acid (PAA) and Hydrogen Peroxide (H 2 O 2 )

Transcription

1 Peracetic Acid (PAA) and Hydrogen Peroxide (H 2 O 2 ) DOC DPD Method Method to mg/l PAA / 0.05 to 5.00 mg/l H 2 O 2 Powder Pillows Scope and application: For testing peracetic acid and hydrogen peroxide in water. Test preparation Instrument-specific information Table 1 shows all of the instruments that have the program for this test. The table also shows requirements that can change between instruments, such as adapter and sample cell requirements. To use the table, select an instrument, then read across to find the applicable information for this test. Table 1 Instrument-specific information Instrument Adapter Sample cell orientation Sample cell DR 6000 The orientation key is toward the arrow on the universal cell adapter DR 5000 A23618 The orientation key is toward the user. DR 3900 LZV846 (A) The orientation key is away from the user. DR or (C) The 1-cm path is aligned with the arrow on the adapter. DR 3800 DR 2800 DR 2700 LZV585 (B) The 1-cm path is aligned with the arrow on the adapter Before starting Samples must be analyzed immediately after collection and cannot be preserved for later analysis. In bright light conditions (e.g., direct sunlight), close the cell compartment, if applicable, with the protective cover during measurements. Review the Safety Data Sheets (MSDS/SDS) for the chemicals that are used. Use the recommended personal protective equipment. Dispose of reacted solutions according to local, state and federal regulations. Refer to the Safety Data Sheets for disposal information for unused reagents. Refer to the environmental, health and safety staff for your facility and/or local regulatory agencies for further disposal information. Items to collect Description Quantity DPD Total Chlorine Reagent Powder Pillows, 25-mL 2 Ammonium Molybdate Reagent Potassium Iodide Solution, 20% Sample cells (For information about sample cells, adapters or light shields, refer to Instrumentspecific information on page 1.) 3 drops 3 drops 3 Refer to Consumable and replacement items on page 4 for order information. 1

2 Sample collection Analyze the samples immediately. The samples cannot be preserved for later analysis. Test procedure PAA and Hydrogen Peroxide Start 1. Start program 790 PAA. For information about sample cells, adapters or light shields, refer to Instrument-specific information on page Prepare the blank: Fill a sample cell to the 10 ml mark with sample. 3. Clean the blank sample cell. 4. Insert the blank into the cell holder. Zero 5. Push ZERO. The display shows 0.0 mg/l PAA. 6. Prepare the sample: Fill a second sample cell to the 10 ml mark with sample. 7. Add the contents of one DPD Total Chlorine Powder Pillow for 25 ml samples to the sample. 8. Start the instrument timer. A 1 minute reaction time starts. Immediately go to the next step. Read 9. Put the stopper on the sample cell. Shake the sample cell about 20 seconds to dissolve the reagent. Invert slowly to remove air bubbles. 10. Clean the sample cell during the reaction time. 11. Insert the prepared sample into the cell holder. 12. When the timer expires, push READ. Results show in mg/l PAA. Do not wait more than 60 seconds to read the sample. Keep the sample cell in the cell holder and continue to the next step. 2 PAA and H 2 O 2, DPD Method (10.00 mg/l PAA, 5.00 mg/l H 2 O 2 )

3 Start Zero 13. Start program 791 H2O With the reacted PAA sample in the cell holder, push ZERO. The display shows 0.0 mg/l H 2 O Prepare the sample: Fill a third sample cell to the 10 ml mark with sample. 16. Add 3 drops of the Potassium Iodide Solution. 17. Add 3 drops of the Ammonium Molybdate Reagent. 18. Put the stopper on the sample cell. Invert the sample cell to mix. 19. Start the instrument timer. A 6 minute reaction time starts. 20. When the timer expires, add one DPD Total Chlorine Powder Pillow for 25 ml samples to the sample. 21. Put the stopper on the sample cell. Shake the sample cell to dissolve the reagent. A pink color shows when PAA and/or H 2 O 2 is in the sample. 22. Start the instrument timer. A 30 second reaction time starts. Make sure that the powder has fully dissolved and that there are no air bubbles. Invert slowly to remove air bubbles. 23. Clean the sample cell during the reaction time. 24. Insert the prepared sample into the cell holder. PAA and H 2 O 2, DPD Method (10.00 mg/l PAA, 5.00 mg/l H 2 O 2 ) 3

4 Read 25. When the timer expires, push READ. Results show in mg/l H 2 O 2. Do not wait more than 60 seconds to read the sample. Interferences Interfering substance Acidity Alkalinity Bromine, Br 2 Chlorine Dioxide, ClO 2 Inorganic chloramines Chloramines, organic Interference level More than 150 mg/l CaCO 3. The full color may not develop or the color may fade instantly. Adjust to ph 6 7 with 1 N Sodium Hydroxide. Measure the amount to add on a separate sample aliquot, then add the same amount to the sample that is tested. Correct the test result for the dilution from the volume addition. More than 250 mg/l CaCO 3. The full color may not develop or the color may fade instantly. Adjust to ph 6 7 with 1 N Sulfuric Acid. Measure the amount to add on a separate sample aliquot, then add the same amount to the sample that is tested. Correct the test result for the dilution from the volume addition. May interfere Hardness No effect at less than 1000 mg/l as CaCO 3 Manganese, Oxidized (Mn 4+, Mn 7+ ) or Chromium, Oxidized (Cr 6+ ) Ozone Chlorine Highly buffered samples or extreme sample ph May interfere Can prevent the correct ph adjustment (of the sample) by the reagents. Sample pretreatment may be necessary. Summary of method Total DPD reacts with PAA to form a pink color. Hydrogen peroxide does not interfere with the PAA reaction. The hydrogen peroxide reaction requires the addition of catalysts and a longer reaction time. The measurement wavelength is 530 nm. Consumable and replacement items Required reagents Description Quantity/Test Unit Item no. DPD Total Chlorine Reagent Powder Pillow, 25-mL 2 100/pkg Ammonium Molybdate Reagent 3 drops 100 ml MDB Potassium Iodide Solution, 20% 3 drops 100 ml PAA and H 2 O 2, DPD Method (10.00 mg/l PAA, 5.00 mg/l H 2 O 2 )

5 Optional reagents and apparatus Description Unit Item no. DPD Total Chlorine Reagent Powder Pillows, 25 ml 1000/pkg Pipet, adjustable volume, ml each BBP065 Pipet tips, for ml pipet 75/pkg BBP068 Dropper, LDPE, ml 20/pkg PAA and H 2 O 2, DPD Method (10.00 mg/l PAA, 5.00 mg/l H 2 O 2 ) 5

6 FOR TECHNICAL ASSISTANCE, PRICE INFORMATION AND ORDERING: In the U.S.A. Call toll-free Outside the U.S.A. Contact the HACH office or distributor serving you. On the Worldwide Web HACH COMPANY WORLD HEADQUARTERS Telephone: (970) FAX: (970) Hach Company/Hach Lange GmbH, All rights reserved. 02/2018, Edition 2